Rapid advances are occurring in various electronic devices especially display devices that are used for various communicational, financial, and archival purposes. For such uses as touch screen panels, electrochromic devices, light emitting diodes, field effect transistors, and liquid crystal displays, conductive films are essential and considerable efforts are being made in the industry to improve the properties of those conductive films.
There is a particular need to provide touch screen displays and devices that contain improved conductive film elements. Currently, touch screen displays use Indium Tin Oxide (ITO) coatings to create arrays of capacitive areas used to distinguish multiple point contacts. ITO coatings have significant short comings. Indium is an expensive rare earth metal and is available in limited supply from very few sources in the world. ITO conductivity is relatively low and requires short line lengths to achieve adequate response rates. Touch screens for large displays are broken up into smaller segments to reduce the conductive line length to an acceptable resistance. These smaller segments require additional driving and sensing electronics. In addition ITO is a ceramic material, is not readily bent or flexed, and requires vacuum deposition with high processing temperatures to prepare the conductive layers.
Silver is an ideal conductor having conductivity 50 to 100 times greater than ITO. Unlike most metal oxides, silver oxide is still reasonably conductive and this reduces the problem of making reliable electrical connections. Silver is used in many commercial applications and is available from numerous sources. It is highly desirable to make conductive film elements using silver as the source of conductivity, but it requires considerable development to obtain the optimal properties.
U.S. Patent Application Publication 2011/0308846 (Ichiki) describes the preparation of conductive films formed by reducing a silver halide image in conductive networks with silver wire sizes less than 10 μm, which conductive films can be used to form touch panels in displays.
In addition, U.S. Pat. No. 3,464,822 (Blake) describes the use of a silver halide emulsion in a photographic element to form a conductive silver surface image by development and one or more treatment baths after development.
Improvements have been proposed for providing conductive patterns using photosensitive silver salt compositions such as silver halide emulsions as described for example in U.S. Pat. No. 8,012,676 (Yoshiki et al.).
U.S. Pat. No. 7,943,291 (Tokunaga et al.) describes photosensitive materials that can be used to prepare conductive silver-containing films.
U.S. Ser. No. 14/265,418 described above provided an improvement in this technology with duplex silver halide conductive film element precursors containing an immobilized UV radiation absorber in the outermost hydrophilic overcoat. Such duplex precursors are used to provide unique conductive silver images on each side of the transparent substrate. However, to reduce “crosstalk” from one photosensitive side to the other photosensitive during imagewise exposure from both sides, these silver halide conductive film element precursors included about 300 mg/m2 (0.9 mmol/m2) of UV absorbing agents in filter layers on both sides of the transparent substrate.
While the crosstalk can be reduced in such manner when the amount of UV absorbing agents is high enough, there is a danger that the chosen UV absorbing agent has a broad enough absorption that it also absorbs in the “blue” region of the electromagnetic spectrum (for example greater than 400 nm). When this occurs, the resulting precursor exhibits undesirable yellow coloration.
There is a need to both reduce crosstalk during imagewise exposure using UV absorbing agents such as in UV filter layers without causing unwanted yellowness in the precursor.